Larry Ellison explains why Microsoft and Amazon are going for Oracle's throat

Oracle has been under attack for the last couple of days, and Oracle co-founder Larry Ellison told Wall Street analysts he's neither surprised nor particularly worried.

Still, maybe he should be.

Microsoft made a direct play for Oracle's customers by telling them they can switch to Microsoft's database for "free." (When you dig into the offer, it requires customers to sign up for Microsoft's cloud database as well as for Microsoft's version of an extended warranty, known as Software Assurance.)

Also this week, Amazon announced that its Oracle-killer service was out of beta and open to all. This is the AWS Database Migration Service (DMS) Amazon announced in October that Amazon promises will easily move Oracle's customers to Amazon's database in the Amazon Web Services cloud.

In fact, Microsoft's offer seems to be aimed at customers contemplating moving to Amazon, since Microsoft's database has historically been less expensive than Oracle and Microsoft's offer also includes a "migration tool."

Meanwhile Oracle announced quarterly earnings. While its cloud application business is growing nicely, revenues for its on-premises software, including the database that Microsoft and Amazon are attacking, were down 11% in constant currency, and that's "3% below Street expectations," says analyst Joel Fishbein from BTIG.

When asked about about Microsoft And Amazon, Ellison answered with a shrug:

People are coming after us because we are by far the leader in database. If you are in the database business, the only one you can go after is us.

So of course Amazon, if they are going to be in the database business, is coming after us. And of course Microsoft wants to be bigger in the database, they have to come after us. We're the biggest player. We see our customers with literally of millions of applications and millions of users on those applications built on the Oracle database wanting to move those applications into the cloud and we do that very well.

Ellison explained that it's not just a matter of moving from one database to another. "If you want to move to an Amazon database, and they have a couple, you have to rewrite your app, that's a huge barrier."

And he's historically been right. That kind of "stickiness" with its database is what caused Oracle to grow into the market leader.

But the new "migration tools" Microsoft and Amazon offer as part of their offers could make that whole process easier.

Microsoft Cloud and Enterprise Corporate VP Takeshi Numoto tells Business Insider that its offer has generated a lot of excitement among Oracle customers. "The level of frustration I've seen in their customers has been very high," Numoto says.

Meanwhile, at the very moment Ellison was downplaying Amazon, Amazon had issued a press release announcing that during the beta phase alone, 1,000 Oracle customers have already taken Amazon up on the offer and jumped ship from Oracle to AWS.

Disclosure: Jeff Bezos is an investor in Business Insider through hispersonal investment company Bezos Expeditions.